Babies of a ferocious group of carnivorous dinosaurs, including T-rex, were huge, with full teeth and claws and were “born ready” to be killed, according to an analysis of recently discovered fetal remains.
The fossils belong to two species in the group called tyrannosaurs, which were the crested predators in Asia and North America during the Cretaceous period at the end of the age of the dinosaurs.
The remains consist of a 3-cm-long, 77-million-year-old jaw bone found in Montana that may have belonged to a species called Daspletosaurus and a 72-million-year-old claw discovered in the Canadian province of Alberta that may have come from Albertosaurus.
Both were slightly smaller cousins to the largest known dinosaur, Tyrannosaurus-rex, which was over 12 meters (40 feet) long and weighed about seven tons.
Fossils indicated that these fossils were larger than any other known dinosaur pups – 1 meter (3 feet) long, or the size of a medium-sized dog – that hatched than what should have been a massive egg, possibly exceeding the largest of 43 cm (17 inches) in length. ). Dinosaur eggs currently known.
The jaw has distinctive tyrannosaur features, including a deep groove inside and a prominent chin.
University of Edinburgh paleontologist Greg Vanston, lead author of the research published in the Canadian Journal of Geosciences, said scientists were amazed at how similar embryonic bones were to older and juvenile tyrannosaurs, and indicated that the jaws boasted functional teeth.
“Although we cannot get a complete picture, what we see looks very similar to adults,” Funston said.
Vanston added that it appears that tyrannosaurs “were born ready to hunt, and indeed have some major adaptations that have given tyrannosaurs their powerful bites.”
“So it is possible that they were able to hunt very quickly after birth, but we need more excavations to find out just how fast that is.”